The invention concerns a coating material based on modified polysilsesquioxanes (highly crosslinked materials, for example, with the empirical formula RSiO1.5), their synthesis and use of the coating material to coat surfaces, especially porous polymers, to achieve oleophobic properties with high temperature stability. The invention also concerns a material coated with this coating material and its applications, as well as an aeration and deaeration element.
Polymer surfaces typically have hydrophobic, but not oleophobic, properties and are wettable for liquids with low surface tension (solvents). Even microporous polytetrafluoroethylene (PTFE) with known high hydrophobic and oleophobic properties is wettable by liquids with surface tensions  less than 28 mN/m (cf. EP 0,581,168).
Numerous fluorine-containing coating compositions for oleophobizing of polymer or porous surfaces are already known, which, however, leave room for improvement, especially in degree of olephobism, temperature stability and oleophobism at elevated temperature.
Coatings based on fluorinated alkyl (meth)acrylates for coating of polyolefins (PP,PE) are described in EP 0,581,168 (Mitsubishi).
Oleophobic coating of microporous (ePTFE) Teflon AF is described in EP 0,561,875.
WO 92/21715 describes the use of perfluoropolyether as oil-repellent coating for microporous polymers. Silicon alkoxides with perfluoropolyether side chains for dirt-repellent coating of silicone surfaces are described in Japanese Application JP 4-213384.
Coating materials based on mixtures of alkoxysilanes, alkoxysilanes with organic nonhydrolyzable side groups and silanes with perfluorinated side groups, which carry perfluorinated groups enriched on the air surface after crosslinking, are described in EP 0 587 667. R. Kasemann et al., New J. Chem., 1994, 18 page 1117, describes such functional coatings produced via the sol-gel process.
Only a method for production of a gel from an inorganic oxide is know from WO 97/01508, in which at least one fluorinated inorganic oxide precursor is mixed with a fluorinated acid. Addition of a fluorinated solvent is absolutely essential. These are cost-intensive and environmentally relevant. It is also disclosed that a layer of material produced in this way is used as an xe2x80x9cadhesion aidxe2x80x9d for a fluoropolymer layer. Possible use of the coating for oleophobization is not described. WO 97/01599 describes a composition from a fluoropolymer and an inorganic oxide produced as described in WO 97/01508.
The task according to the invention consists of preparing a coating material having high oleophobism.
Another task is to apply a coating material to substrate surfaces, especially porous polymers, in which the coated substrate exhibits high oleophobism.
Another task is to produce a coated substrate with high oleophobism, having high temperature stability.
A further task is to produce a coated substrate, in which only a slight change in permeability of the substrate develops from the coating or the porosity is essentially uninfluenced, in the case of porous substrates.
A next task is to produce such a coating material without having to use environmentally relevant, especially fluorinated, solvents.
A last task is to devise an aeration and deaeration element that has versatile use and prevents entry or passage of liquids.
The coating material according to the invention comprises condensates of at least one compound A with general formula RaMZb (a=0-3; b=1-4; a+b=3-4), in which R is a nonhydrolyzable organic group, and at least one compound B of the general formula Rxe2x80x2xMZy (x=1-3; y=1-3; x+y=3-4), in which Rxe2x80x2 is a nonhydrolyzable organic group and at least one Rxe2x80x2 contains a perfluoropolyether structure separated from M by at least two atoms, in which M is an element chosen from groups IIIA-VA or groups IIB-IVB of the periodic system and Z is a hydrolyzable organic group, and in which at least one R is not identical to at least one Rxe2x80x2.
The coating material according to the invention can be applied to a 35 substrate. In a preferred variant the substrate is a porous polymer, especially a textile fabric or a fluoropolymer or fluoropolymer blend, especially in microporous form, like expanded polytetrafluoroethylene (ePTFE).
The invention also offers a process for production of a coating material, in which at least one compound A of the general formula RaMZb (a=0-3; b=1-4; a+b=3-4), in which R is a nonhydrolyzable organic group, and at least one compound B of the general formula Rxe2x80x2xMZy(x=1-3; y=1-3;x+y=3-4), in which Rxe2x80x2 is a nonhydrolyzable organic group, and at least one Rxe2x80x2 contains a perfluoropolyether structure separated from M by at least two atoms, in which M is an element chosen from groups IIIA-VA or groups IIB-IVB of the periodic system and Z is a hydrolyzable organic group, and in which at least one R is not identical to at least one Rxe2x80x2, are mixed.
The invention also makes available a process for coating of a substrate, in which a coating material according to the invention is applied to a substrate and cured. The present invention also creates an aeration and deaeration element that comprises a coated material, having a substrate and a coating material applied to at least one surface of the substrate, in which the coating material contains condensates of a least one compound A of general formula RaMZb (a=0-3; b=1-4; a+b=3,4), in which R is a nonhydrolyzable organic group, and at least one compound B of the general formula Rxe2x80x2xMZy (x=1-3; y=1-3; x+y=3,4), in which Rxe2x80x2 is a nonhydrolyzable organic group, and at least one Rxe2x80x2 contains a perfluoropolyether structure separated from M by at least two atoms, in which M is an element chosen from groups IIIA-VA or groups IIB-IVB of the periodic system and Z is a hydrolyzable organic group, and in which at least one R is not identical to at least one Rxe2x80x2.